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Noise caused by mechanical vibration of the elements of an electron tube, component, or system. Also known as microphonism.



the phenomenon of undesirable changes in the parameters of an electric or magnetic circuit or of an electronic device that is caused by mechanical vibrations, shocks, and particularly by acoustic vibrations.

Microphonics produce interference during the operation of electronic apparatus, such as electrical audio-frequency amplifiers and superheterodyne radio receivers; they are heard as a characteristic ringing in the loudspeaker. In an amplifier they are caused mainly by movement of the electrodes in the input vacuum tube; in radio receivers, by the movement of the plates in the variable capacitor of the heterodyne circuit. The effect may be stimulated by a sound wave from a loudspeaker. It can be prevented by cushioning the tube sockets and the capacitor supports, by making the tube structure more rigid, or by avoiding the direct action of sound waves from a loudspeaker on the radio components. Microphonics are absent in semiconductor devices. The effect received its name because of the analogy between the physical processes in the effect and in a microphone.

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(4) The possibility of discriminating noise from electromagnetic disturbances and microphonic effect.
Modifications of cochlear microphonics and action potentials by KCl solution and by direct currents.
Microphonics, which are acoustic vibrations that traverse an oscillator package and its circuits, and cause changes in phase and frequency, are dealt with in the DCSOs series VCOs through innovative design topology.
[7,8] They found that perfusion of air into the scala tympani resulted in a drastic decrease in the cochlear microphonics and in the amplitude of the compound action potential.
If you go the tube preamp route check for excessive microphonics (it can drive one crazy!) by rapping the preamp case with your knuckles.
MMIC VCOs can minimize the problems associated with microphonics, vibrations and temperature anomalies because they eliminate chip-to-chip interconnections between the resonator and negative resistance element.
The surface transverse wave (STW) VCO is designed for fixed phase-locked loop (PLL) applications and offers system benefits in the areas of low noise floor, high fundamental frequencies and resistance to microphonics. It is for these reasons that until now, most applications for phase-locked surface acoustic wave (SAW) and STW VCOs have been military.
The A4 series precision trimmer capacitors features a patented solid dielectric design that eliminates the possibility of intermittent shorting and microphonics. The rugged construction features positive stops at minimum and maximum capacitance.
This design inherently eliminates any possibility of shorting, voltage breakdown or capacitive microphonics, which are serious potential problems in conventional 30 pF air-dielectric piston trimmer capacitors.
Extensive testing has been performed on these oscillators to qualify them for MSK, 16 QAM and 64 QAM digital radios where there is little tolerance for microphonics and phase hits.
Two metallic probes (slugs) made of beryllium copper, dielectrically coated on the bottom and axially slotted for good ground contact and low microphonics, are mounted on each vertical axis.
The utilized transmission line and new (slotted) RF slug provides full coverage of the 6 to 40 GHz band, as shown in Figure 1, acceptable residual reflection (-20 dB), good microwave reproducibility, low sensitivity to vibrations (microphonics) and reasonable manufacturability.